AT45DB021E datasheet(22/70 Pages) RENESAS

22 / 70 page

DS-AT45DB021E-8789 Rev. L

Page 22

8/11/22

AT45DB021E Datasheet

9.1.2

Disable Sector Protection

To disable the sector protection, a 4-byte command sequence of 3Dh, 2Ah, 7Fh, and 9Ah must be clocked into the

device. After the last bit of the opcode sequence has been clocked in, the CS pin must be deasserted to disable

the sector protection.

Figure 6. Disable Sector Protection

9.2

Hardware Controlled Protection

Sectors specified for protection in the Sector Protection Register and the Sector Protection Register itself can be

protected from program and erase operations by asserting the WP pin and keeping the pin in its asserted state.

The Sector Protection Register and any sector specified for protection cannot be erased or programmed as long

as the WP pin is asserted. In order to modify the Sector Protection Register, the WP pin must be deasserted. If the

WP pin is permanently connected to GND, then the contents of the Sector Protection Register cannot be

changed. If the WP pin is deasserted or permanently connected to VCC, then the contents of the Sector Protection

The WP pin overrides the software controlled protection method but only for protecting the sectors.

Example: If the sectors were not previously protected by the Enable Sector Protection command, then simply

asserting the WP pin would enable the sector protection within the maximum specified tWPE time. When the WP

pin is deasserted, however, the sector protection would no longer be enabled (after the maximum specified tWPD

time) as long as the Enable Sector Protection command was not issued while the WP pin was asserted. If the

Enable Sector Protection command was issued before or while the WP pin was asserted, then simply deasserting

the WP pin would not disable the sector protection. In this case, the Disable Sector Protection command would

need to be issued while the WP pin is deasserted to disable the sector protection. The Disable Sector Protection

command is also ignored whenever the WP pin is asserted.

The incorporated noise filter helps protect against spurious noise that can inadvertently assert or deassert the WP

pin.

Figure 7 and Table 7 detail the sector protection status for various scenarios of the WP pin, the Enable Sector

Protection command, and the Disable Sector Protection command.

Figure 7. WP Pin and Protection Status

Table 6. Disable Sector Protection Command

Command

Byte 1

Byte 2

Byte 3

Byte 4

Disable Sector Protection

3Dh

2Ah

7Fh

9Ah

3Dh

2Ah

7Fh

9Ah

Each transition represents eight bits

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